This new mint was developed in a mint breeding program in which the primary objective was to develop a Mitcham type peppermint variety having a specific oil composition, acceptable yield and resistant to mint diseases. The new variety is as susceptible to mint wilt (soil borne fungus Verticillium dahliae) as its parent, but more resistant to mint rust (air-borne fungus Puccinia menthae). No rust has been observed on ‘Boulder Mint’ since 2007 and subsequent years. ‘Boulder Mint’ has a higher yield of oil than the control variety, ‘Black Mitcham’, in test plots since 2007. This plant was selected from a population of mint seedlings in research plots on land near Monmouth, Oreg. and initially identified as 07-A3-5A.